A microelectronic package comprises a microelectronic die electrically interconnected with a carrier substrate, and one or more other elements, such as electrical interconnects, a die lid, a heat dissipation device, among others. An example of a microelectronic package is an integrated circuit microprocessor. A microelectronic die comprises multiple interconnected microcircuits within a single carrier to perform electronic circuit functions. A microelectronic device is defined as a microelectronic die with microcircuits electrically interconnected with electrically conductive pathways on the surface of or within a carrier substrate. Electrical communication between the microcircuits and external components may be provided by electrically interconnecting the electrically conductive pathways of the carrier substrate with electrically conductive pathways of a system substrate. An example of a system substrate is a printed circuit board (PCB), which, in some applications, is referred to as a motherboard.
Microelectronic packages are designed to have specific electrical characteristics specified by the desired operating characteristics of the attached microelectronic die and the specific application where the microelectronic package is to be used. Some of these electrical characteristics include operating voltage and frequency. The production costs to produce individual microelectronic package designs for each of the desired electrical characteristics for each of the ever-evolving microelectronic dice is prohibitive. Therefore, microelectronic packages are commonly designed to be used for many different applications by providing some degree of control over setting the desirable electrical characteristics of the microelectronic device.
For example, a microelectronic package in the form of an integrated circuit microprocessor might be adapted to be used in a desktop as well as a laptop computer application. For optimum performance, each application might require the microelectronic package to operate with different die core voltage and Front Side Bus (FSB) frequency values. Therefore the microelectronic device is engineered to provide the ability to control or set these values for a particular application during manufacture and assembly of the microelectronic package.
A common method to control the electrical characteristics of the microelectronic package involves the use of settable bits. Settable bits can be thought of as micro-switches that are either open or closed used to control a logic circuit using one or more on/off signals. The on/off signals are interpreted by the logic circuit to cause the microelectronic device to operate with the desired electrical characteristics. For example, one settable bit has two possible electrical states; one on or open and one off or closed. Therefore, the logic circuit may control the microelectronic device to operate with one of two possible electrical characteristics. Two settable bits will have four possible electrical states which may control the microelectronic device to operate with one of four possible electrical characteristics, and so forth.
In one example illustrating the setting of the die core voltage using settable bits on the carrier substrate of the microelectronic package, the carrier substrate is engineered to provide one or more pairs of open circuit electrical contacts known as voltage identification (voltage ID or VID) bits. One electrical contact of each pair is coupled to electrical ground (Vss) while the other electrical contact is connected to a voltage regulator circuit (VRC). A VID bit is closed by soldering a 0-ohm resistor across the pair of electrical contacts electrically shorting the circuit. A closed bit is interpreted by the VRC to be a logical or binary zero (“0”). A VID bit in its open state is interpreted to be a logical or binary one (“1”).
The electrical state of the VID bits is interpreted by the VRC, which responds with a predetermined voltage value. The VRC response to the electrical state of the VID bits is predetermined by the microelectronic device's design or programming. In a four (4) bit configuration, up to sixteen (2.super.4) possible VID bit combinations can be used to set different VRC responses.
The ongoing goals of the computer industry are toward higher performance, lower cost and increased miniaturization of microelectronic packaging. The use of 0-ohm resistors coupled to electrical contacts on the carrier substrate does not lend itself to current and future packaging performance goals. The resistors are inherently bulky taking up valuable real estate and volume that interferes with achieving the goal of microelectronic package miniaturization. Applying the resistors across the pairs of contacts requires accurate placement by complex production equipment on a surface of the carrier substrate otherwise crowded with other connectors and components.
New configurations and methods are needed for providing settable bits on the carrier substrate to control the microelectronic package's electrical characteristics. They must provide for exceptionally small scale integration, not interfere with the electrical interface of other components within the microelectronic package, be highly configurable to provide for many control variations, easily and quickly configurable without the need for complex machinery, and inexpensive to manufacture.